"Will Smith can not come back because he's too expensive, but he'd also be too much of a marquee name," said Emmerich, while promoting his latest film, "White House Down." "It would be too much.

"We have like maybe half of the people that you know would know from the first film (in the script) and the other half people who are new," the German director added.

Emmerich says that the sequel, which is scheduled to come out July 3, 2015, will be the first part of a two-part story, tentatively titled ID Forever. He also joked that he thinks some aliens might be back for his alien invasion movie. They are cheap enough, it seems.